Transmission method and apparatus

Abstract

The present application provides a transmission method and apparatus. The method includes: a first terminal device obtains information of N SL transmission units, where the N SL transmission units are used for transmitting a data packet of a unicast connection or a multicast communication group by SL; the first terminal device uses an unused SL transmission unit among the N SL transmission units to transmit the data packet to a second terminal device through a HARQ process used by the unicast connection or the multicast communication group; the second terminal device sends a HARQ feedback result to the first terminal device according to a decoding result; in a case where the first terminal device does not receive the HARQ feedback result or the received HARQ feedback result indicates that the data packet transmission fails, the first terminal device uses the next unused SL transmission unit among the N SL transmission units to retransmit the data packet. By introducing a HARQ feedback retransmission mechanism and a corresponding resource allocation method in SL transmission, the reliability of the data packet transmitted by SL is improved.

Description

Technical Field

[0001] This application relates to communication technologies, and in particular, to a transmission method and apparatus. Background Art

[0002] Vehicle-to-everything (V2X) technology enables communication between vehicles and the outside world. V2X includes vehicle-to-infrastructure (V2I) services, vehicle-to-network (V2N) services, vehicle-to-pedestrian (V2P) services, and vehicle-to-vehicle (V2V) services. For V2X based on the Long Term Evolution (LTE) network, there are two communication interfaces: Uu and PC5. The Uu interface is used for communication between a terminal device and a resource scheduling device, and the PC5 interface is used for sidelink (SL) communication between terminals. Both of the above two communication interfaces can be used to transmit V2X data.

[0003] V2X based on the LTE network defines two resource allocation modes: mode-3 and mode-4. In mode-3, when a terminal device has SL data to transmit, the base station allocates SL transmission resources for the terminal device from a resource pool through scheduling. In mode-4, when a terminal device has SL data to transmit, the terminal device selects SL transmission resources from the resource pool as needed. To ensure the reliability of SL transmission, existing SL transmission supports blind retransmission at the Medium Access Control (MAC) layer. When the number of blind retransmissions is determined to be 1, blind retransmission will be performed regardless of whether the initial transmission is successful. Whether it is mode-3 or mode-4, when a terminal device obtains the transmission resources for a Medium Access Control Protocol Data Unit (MAC PDU), the time-frequency resources for the initial transmission and retransmission of the MAC PDU are uniquely determined.

[0004] In the New Radio (NR) network, V2X needs to support the transmission of high-reliability services, such as ensuring a transmission reliability of up to 99.999% for each data packet. In the prior art, relying solely on blind retransmission cannot guarantee the reliability of each data packet. Summary of the Invention

[0005] The present application provides a transmission method and apparatus, which improve the reliability of data packets in SL transmission by introducing a HARQ feedback retransmission mechanism and a corresponding resource allocation method in SL transmission.

[0006] A first aspect of the present application provides a transmission method, which is applied to a first terminal device and includes:

[0007] The first terminal device obtains information of N SL transmission units, where the N SL transmission units are used for transmitting data packets to be transmitted in a unicast connection or a multicast communication group of the SL, and the SL is a wireless communication link between the first terminal device and a second terminal device, where N is an integer greater than or equal to 1;

[0008] The first terminal device transmits the data packet using an unused SL transmission unit among the N SL transmission units through the HARQ process used by the unicast connection or the multicast communication group;

[0009] In a case where the first terminal device does not receive a HARQ feedback result or the received HARQ feedback result indicates that the data packet transmission fails, the first terminal device transmits the data packet using the next unused SL transmission unit among the N SL transmission units.

[0010] Through the HARQ feedback retransmission mechanism, high reliability of SL transmission can be ensured.

[0011] In an example, the first terminal device obtaining information of N SL transmission units includes:

[0012] The first terminal device receives downlink control information DCI sent by a resource scheduling device, where the DCI includes information of the N SL transmission units, and the information of the N SL transmission units includes identification information of carriers where the N SL transmission units are located and information of time-frequency resources occupied by the N SL transmission units.

[0013] By scheduling multiple SL transmission units for a terminal device at one time, the resource scheduling device can avoid large delays and waste of resource requests caused by the terminal device requesting resources every time it retransmits.

[0014] In another example, the first terminal device obtaining information of N SL transmission units includes:

[0015] The first terminal device determines information of the N SL transmission units from a resource pool preconfigured by the resource scheduling device, where the information of the N SL transmission units includes identification information of carriers where the N SL transmission units are located and information of time-frequency resources occupied by the N SL transmission units.

[0016] By pre-configuring a resource pool for the terminal device, the large latency caused by requesting resources from the resource scheduling device and the waste of requested resources can be reduced.

[0017] In one example, the DCI further includes any one or more of the following information: communication type, identification of the HARQ process, and identification of the partial bandwidth;

[0018] The communication type is a unicast communication type or a multicast communication type.

[0019] In one example, it further includes:

[0020] The first terminal device determines the unicast connection or the multicast communication group from the unicast connections or multicast communication groups that have data packets to be transmitted and are transmitted on the carrier where the N SL transmission units are located, according to the communication type;

[0021] The first terminal device determines the HARQ process used by the unicast connection or the multicast communication group from a group of HARQ processes corresponding to the SL carrier where the N SL transmission units are located of the unicast connection or the multicast communication group, according to the identification of the HARQ process included in the DCI.

[0022] A second aspect of the present application provides a transmission method, which is applied to a first terminal device and includes:

[0023] The first terminal device obtains information of a first sidelink (SL) transmission unit, where the first SL transmission unit is used to transmit data packets to be transmitted of a unicast connection or a multicast communication group, and the SL is a wireless communication link between the first terminal device and a second terminal device;

[0024] The first terminal device transmits the data packet using the first SL transmission unit through a hybrid automatic repeat request (HARQ) process corresponding to the unicast connection or the multicast communication group;

[0025] In the case where the data packet transmission fails, the first terminal device obtains information of a second SL transmission unit;

[0026] The first terminal device retransmits the data packet using the second SL transmission unit.

[0027] Through the HARQ feedback retransmission mechanism, the high reliability of SL transmission can be ensured. The terminal device obtains retransmission resources only when determining retransmission, which can avoid waste of resources.

[0028] In one example, the first terminal device obtaining information of the first SL transmission unit includes:

[0029] The first terminal device receives first downlink control information (DCI) sent by a resource scheduling device. The first DCI includes information about the first SL transmission unit, and the information about the first SL transmission unit includes identification information of the carrier where the first SL transmission unit is located and information about the time-frequency resources occupied by the first SL transmission unit;

[0030] In the case where the data packet transmission fails, the first terminal device obtains information about a second SL transmission unit, including:

[0031] The first terminal device receives second DCI sent by the resource scheduling device. The second DCI includes information about the second SL transmission unit, and the information about the second SL transmission unit includes identification information of the carrier where the second SL transmission unit is located and information about the time-frequency resources occupied by the second SL transmission unit. The second SL transmission unit is allocated by the resource scheduling device according to the HARQ feedback result reported by the first terminal device or the second terminal device.

[0032] In another example, the first terminal device obtaining the information about the first SL transmission unit or the information about the second SL transmission unit includes:

[0033] The first terminal device determines the information about the first SL transmission unit or the information about the second SL transmission unit from a resource pool pre-configured by the resource scheduling device. The information about the first SL transmission unit includes identification information of the carrier where the first SL transmission unit is located and information about the time-frequency resources occupied by the first SL transmission unit. The information about the second SL transmission unit includes identification information of the carrier where the second SL transmission unit is located and information about the time-frequency resources occupied by the second SL transmission unit.

[0034] In one example, the first DCI further includes at least one of the following information: information about the communication type, the identification of the HARQ process, and the identification of the partial bandwidth;

[0035] The communication type is a unicast communication type or a multicast communication type.

[0036] In one example, it further includes:

[0037] The first terminal device determines the unicast connection or the multicast communication group from the unicast connections or multicast communication groups that have data packets to be transmitted and are transmitted on the carrier where the first SL transmission unit is located according to the communication type;

[0038] The first terminal device determines the HARQ process used by the unicast connection or the multicast communication group from a set of HARQ processes corresponding to the SL carrier where the first SL transmission unit is located, according to the identifier of the HARQ process included in the first DCI, for the unicast connection or the multicast communication group.

[0039] A third aspect of this application provides a transmission method, including:

[0040] A resource scheduling device sends information of N sidelink (SL) transmission units to a first terminal device, where the N SL transmission units are used for transmitting data packets to be transmitted for a unicast connection or a multicast communication group on the SL, and the SL is a wireless communication link between the first terminal device and a second terminal device, where N is an integer greater than or equal to 1;

[0041] The resource scheduling device receives a HARQ feedback result sent by the first terminal device or the second terminal device.

[0042] In one example, the resource scheduling device sending information of N sidelink (SL) transmission units to a first terminal device includes:

[0043] The resource scheduling device sends downlink control information (DCI) to the first terminal device, where the DCI includes information of the N SL transmission units, and the information of the N SL transmission units includes identification information of carriers where the N SL transmission units are located and information of time-frequency resources occupied by the N SL transmission units.

[0044] A fourth aspect of this application provides a transmission method, applied to a second terminal device, including:

[0045] The second terminal device receives a data packet and a scheduling control information (SCI), where the SCI includes one or more of the following information: communication type, identifier of a unicast connection, or identifier of a multicast communication group;

[0046] The second terminal device determines the unicast connection or the multicast communication group corresponding to this transmission according to the communication type, and / or the identifier of the unicast or the identifier of the multicast communication group, where the communication type is a unicast communication type or a multicast communication type;

[0047] The second terminal device decodes the data packet through a hybrid automatic repeat request (HARQ) process used by the unicast connection or the multicast communication group corresponding to this transmission;

[0048] The second terminal device sends a HARQ feedback result to the first terminal device or the resource scheduling device according to the decoding result, and data is transmitted between the first terminal device and the second terminal device through a sidelink.

[0049] In one example, the SCI further includes an identifier of a HARQ process, an identifier of the first terminal device, and identifier information of an SL carrier carrying the data packet. Before the second terminal device decodes the data packet using the HARQ process corresponding to the unicast connection or multicast communication group for this transmission, it further includes:

[0050] The second terminal device determines the HARQ process used by the unicast connection or multicast communication group for this transmission from a group of HARQ processes corresponding to the SL carrier carrying the data packet of the unicast connection or multicast communication group for this transmission according to the identifier of the HARQ process, the identifier of the first terminal device, the identifier of the unicast connection, or the identifier of the multicast communication group included in the SCI.

[0051] A fifth aspect of the present application provides a transmission device applied to a first terminal device, including:

[0052] An obtaining module, configured to obtain information of N sidelink (SL) transmission units, where the N SL transmission units are used for the SL to send data packets to be transmitted of a unicast connection or a multicast communication group, and the SL is a wireless communication link between the first terminal device and the second terminal device, where N is an integer greater than or equal to 1;

[0053] A sending module, configured to use an unused SL transmission unit among the N SL transmission units to transmit the data packet through a hybrid automatic repeat request (HARQ) process used by the unicast connection or the multicast communication group;

[0054] The sending module is further configured to, when the first terminal device does not receive a HARQ feedback result or the received HARQ feedback result indicates that the data packet transmission fails, use the next unused SL transmission unit among the N SL transmission units to transmit the data packet.

[0055] In one example, the obtaining module is specifically configured to:

[0056] Receive downlink control information (DCI) sent by a resource scheduling device, where the DCI includes information of the N SL transmission units, and the information of the N SL transmission units includes identifier information of carriers where the N SL transmission units are located and information of time-frequency resources occupied by the N SL transmission units.

[0057] In another example, the obtaining module is specifically configured to:

[0058] Determine the information of the N SL transmission units from a resource pool pre-configured by a resource scheduling device, where the information of the N SL transmission units includes identification information of the carriers where the N SL transmission units are located and information of time-frequency resources occupied by the N SL transmission units.

[0059] In one example, the DCI further includes any one or more of the following information: communication type, identification of a HARQ process, and identification of a partial bandwidth;

[0060] The communication type is a unicast communication type or a multicast communication type.

[0061] In one example, it further includes:

[0062] A first determination module, configured to determine the unicast connection or the multicast communication group from unicast connections or multicast communication groups that have data packets to be transmitted and are transmitted on the carriers where the N SL transmission units are located, according to the communication type;

[0063] A second determination module, configured to determine the HARQ process used by the unicast connection or the multicast communication group from a group of HARQ processes corresponding to the SL carriers where the N SL transmission units are located, according to the identification of the HARQ process included in the DCI.

[0064] A sixth aspect of the present application provides a transmission device, applied to a first terminal device, including:

[0065] An acquisition module, configured to acquire information of a first sidelink (SL) transmission unit, where the first SL transmission unit is used to transmit data packets to be transmitted of a unicast connection or a multicast communication group, and the SL is a wireless communication link between the first terminal device and a second terminal device;

[0066] A sending module, configured to transmit the data packet using the first SL transmission unit through a hybrid automatic repeat request (HARQ) process corresponding to the unicast connection or the multicast communication group;

[0067] The acquisition module is further configured to acquire information of a second SL transmission unit when the data packet transmission fails;

[0068] The sending module is further configured to retransmit the data packet using the second SL transmission unit.

[0069] In one example, the acquisition module is specifically configured to:

[0070] Receive the first downlink control information DCI sent by the resource scheduling device, where the first DCI includes information of the first SL transmission unit, and the information of the first SL transmission unit includes identification information of the carrier where the first SL transmission unit is located and information of the time-frequency resources occupied by the first SL transmission unit;

[0071] Receive the second DCI sent by the resource scheduling device, where the second DCI includes information of the second SL transmission unit, and the information of the second SL transmission unit includes identification information of the carrier where the second SL transmission unit is located and information of the time-frequency resources of the second SL transmission unit. The second SL transmission unit is allocated by the resource scheduling device according to the HARQ feedback result reported by the first terminal device or the second terminal device.

[0072] In another example, the obtaining module is specifically configured to:

[0073] Determine the information of the first SL transmission unit or the information of the second SL transmission unit from a resource pool preconfigured by the resource scheduling device, where the information of the first SL transmission unit includes identification information of the carrier where the first SL transmission unit is located and information of the time-frequency resources occupied by the first SL transmission unit, and the information of the second SL transmission unit includes identification information of the carrier where the second SL transmission unit is located and information of the time-frequency resources occupied by the second SL transmission unit.

[0074] In one example, the first DCI further includes at least one of the following information: information of the communication type, identification of the HARQ process, and identification of the partial bandwidth;

[0075] The communication type is a unicast communication type or a multicast communication type.

[0076] In one example, it further includes:

[0077] A first determination module, configured to determine the unicast connection or the multicast communication group from the unicast connections or multicast communication groups that have data packets to be transmitted and are transmitted on the carrier where the first SL transmission unit is located according to the communication type;

[0078] A second determination module, configured to determine the HARQ process used by the unicast connection or the multicast communication group from a group of HARQ processes corresponding to the SL carrier where the first SL transmission unit is located in the unicast connection or the multicast communication group according to the identification of the HARQ process included in the first DCI.

[0079] The seventh aspect of the present application provides a transmission device, which is applied to a resource scheduling device and includes:

[0080] A sending module, configured to send information of N sidelink (SL) transmission units to a first terminal device, where the N SL transmission units are used for transmitting data packets to be transmitted of an SL unicast connection or a multicast communication group, and the SL is a wireless communication link between the first terminal device and a second terminal device, where N is an integer greater than or equal to 1;

[0081] A receiving module, configured to receive a Hybrid Automatic Repeat reQuest (HARQ) feedback result sent by the first terminal device or the second terminal device.

[0082] In one example, the sending module is specifically configured to:

[0083] Send downlink control information (DCI) to the first terminal device, where the DCI includes the information of the N SL transmission units, and the information of the N SL transmission units includes identification information of carriers where the N SL transmission units are located and information of time-frequency resources occupied by the N SL transmission units.

[0084] An eighth aspect of this application provides a transmission device, which is applied to a second terminal device and includes:

[0085] A receiving module, configured to receive a data packet and sidelink control information (SCI), where the SCI includes one or more of the following information: communication type, identification of a unicast connection, or identification of a multicast communication group;

[0086] A first determination module, configured to determine a unicast connection or a multicast communication group corresponding to this transmission according to the communication type, and / or the identification of the unicast or the identification of the multicast communication group, where the communication type is a unicast communication type or a multicast communication type;

[0087] A decoding module, configured to decode the data packet through a Hybrid Automatic Repeat reQuest (HARQ) process used by the unicast connection or the multicast communication group corresponding to this transmission;

[0088] A sending module, configured to send a HARQ feedback result to the first terminal device or a resource scheduling device according to a decoding result, where data is transmitted between the first terminal device and the second terminal device through a sidelink.

[0089] In one example, the SCI further includes an identification of a HARQ process, an identification of the first terminal device, and identification information of an SL carrier carrying the data packet, and further includes:

[0090] A second determination module, configured to determine, according to an identifier of a HARQ process included in the SCI, an identifier of the first terminal device, an identifier of a unicast connection, or an identifier of a multicast communication group, a HARQ process used by the unicast connection or the multicast communication group corresponding to this transmission from a group of HARQ processes corresponding to the SL carrier carrying the data packet for the unicast connection or the multicast communication group corresponding to this transmission.

[0091] In the first to third aspects and the fourth to seventh aspects of this application, multiple groups of HARQ processes are set on the SL carrier where the SL transmission unit is located, and each group of HARQ processes in the multiple groups of HARQ processes can only be used for data transmission of one unicast connection or one multicast communication group; or,

[0092] A group of shared unicast HARQ processes or multicast HARQ processes is set on the SL carrier where the SL transmission unit is located, the shared unicast HARQ processes can be used for data transmission of all unicast connections on the SL carrier where the SL transmission unit is located, and the shared multicast HARQ processes can be used for data transmission of all multicast communication groups on the SL carrier where the SL transmission unit is located.

[0093] In one example, indication information is carried in the SCI of the data packet, and the indication information is used to instruct the second terminal device to perform HARQ feedback;

[0094] Wherein, the indication information is a communication type, and the communication type is a unicast communication type or a multicast communication type; or,

[0095] The indication information is an identifier of the second terminal device or an identifier of the multicast communication group; or,

[0096] The indication information is a value of at least one-bit HARQ feedback field, and the value of the HARQ feedback field is used to indicate whether to perform HARQ feedback.

[0097] In one example, the SCI of the data packet further includes any one or more of the following information: information on resources used for the HARQ feedback result, initial transmission or retransmission indication information, a redundancy version of the data packet, information on a carrier carrying the data packet, information on a partial bandwidth BWP carrying the data packet, an identifier of a HARQ process used by the unicast connection or the multicast communication group, information on the N SL transmission units, an identifier of the unicast connection or an identifier of the multicast communication group, information on a communication type, and an identifier of the first terminal device.

[0098] In the fourth or eighth aspect of the present application, multiple sets of HARQ processes are set on the SL carrier carrying the data packet, and each set of HARQ processes in the multiple sets of HARQ processes can only be used for data transmission of a single unicast connection or a multicast communication group; or,

[0099] A set of shared unicast HARQ processes or multicast HARQ processes is set on the SL carrier carrying the data packet. The shared unicast HARQ process can be used for data transmission of all unicast connections on the SL carrier carrying the data packet, and the shared multicast HARQ process can be used for data transmission of all multicast communication groups on the SL carrier carrying the data packet.

[0100] The ninth aspect of the present application provides a terminal device, including: a processor, a memory, and a transceiver. The memory is used to store instructions, the transceiver is used to communicate with other devices, and the processor is used to execute the instructions stored in the memory, so that the terminal device executes the method described in any one of the first, second, fourth, fifth, sixth, and eighth aspects of the present application.

[0101] The tenth aspect of the present application provides a resource scheduling device, including: a processor, a memory, and a transceiver. The memory is used to store instructions, the transceiver is used to communicate with other devices, and the processor is used to execute the instructions stored in the memory, so that the resource scheduling device executes the method described in the third or seventh aspect.

[0102] Exemplarily, the resource scheduling device provided by the embodiments of the present application or the transmission device applied to the resource scheduling device can be a base station, a node in a radio access network, or other network devices on the network side that provide services for terminal devices.

[0103] The eleventh aspect of the present application provides a computer-readable storage medium. The computer-readable storage medium stores instructions, and when the instructions are executed, the computer is enabled to execute the method described in any one of the first, second, fourth, fifth, sixth, and eighth aspects of the present application.

[0104] The twelfth aspect of the present application provides a computer-readable storage medium. The computer-readable storage medium stores instructions, and when the instructions are executed, the computer is enabled to execute the method described in the third or seventh aspect.

[0105] A thirteenth aspect of the present application provides a computer program product applied to a terminal device. The computer program product includes instructions that, when executed by a computing device, cause the terminal device to execute the method described in any one of the first, second, fourth, fifth, sixth, and eighth aspects of the present application.

[0106] A fourteenth aspect of the present application provides a computer program product applied to a resource scheduling device. The computer program product includes instructions that, when executed by a computing device, cause the resource scheduling device to execute the method described in the third or seventh aspect of the present application.

[0107] A fifteenth aspect of the present application provides a system-on-chip or system chip that can be applied to a terminal device. The system-on-chip or system chip includes: at least one communication interface, at least one processor, and at least one memory. The communication interface, memory, and processor are interconnected through a bus. By executing the instructions stored in the memory, the processor enables the terminal device to execute the method described in any one of the first, second, fourth, fifth, sixth, and eighth aspects of the present application.

[0108] A sixteenth aspect of the present application provides a system-on-chip or system chip that can be applied to a resource scheduling device. The system-on-chip or system chip includes: at least one communication interface, at least one processor, and at least one memory. The communication interface, memory, and processor are interconnected through a bus. By executing the instructions stored in the memory, the processor enables the resource scheduling device to execute the method described in the third or seventh aspect of the present application.

[0109] A seventeenth aspect of the present application provides a communication system that includes any one or several of the above-mentioned first terminal device, second terminal device, and resource scheduling device.

[0110] The transmission method and device provided by this application, the method includes: The first terminal device obtains information of N SL transmission units, and these N SL transmission units are used to transmit a data packet of a unicast connection or a multicast communication group. The first terminal device uses an unused SL transmission unit among the N SL transmission units to transmit the data packet to the second terminal device through the HARQ process used by the unicast connection or the multicast communication group. The second terminal device sends a HARQ feedback result to the first terminal device according to the decoding result. In the case where the first terminal device does not receive the HARQ feedback result or the received HARQ feedback result indicates that the data packet transmission fails, the first terminal device uses the next unused SL transmission unit among the N SL transmission units to retransmit the data packet. By introducing a HARQ feedback retransmission mechanism and a corresponding resource allocation method in SL transmission, the reliability of the data packet transmitted by SL is improved. Description of the Drawings

[0111] Figure 1 It is a schematic diagram of a network architecture applicable to this application;

[0112] Figure 2 It is a schematic diagram of another network architecture applicable to this application;

[0113] Figure 3 It is a signaling flowchart of the transmission method provided in Embodiment 1 of this application;

[0114] Figure 4 It is a signaling flowchart of the transmission method provided in Embodiment 3 of this application;

[0115] Figure 5 It is a schematic diagram of the structure of the transmission device provided in Embodiment 6 of this application;

[0116] Figure 6 It is a schematic diagram of the structure of the transmission device provided in Embodiment 7 of this application;

[0117] Figure 7 It is a schematic diagram of the structure of the transmission device provided in Embodiment 8 of this application;

[0118] Figure 8 It is a schematic diagram of the structure of the transmission device provided in Embodiment 9 of this application;

[0119] Figure 9 It is a schematic diagram of the structure of the terminal device provided in Embodiment 10 of this application;

[0120] Figure 10 It is a schematic diagram of the structure of the resource scheduling device provided in Embodiment 11 of this application. Detailed Embodiments

[0121] Figure 1A schematic diagram of a network architecture applicable to this application. In this network architecture, there are a base station and two terminal devices: a first terminal device and a second terminal device. The first terminal device and the second terminal device are within the coverage range of the same base station. Figure 2 A schematic diagram of another network architecture applicable to this application. In this network architecture, there are a first base station, a second base station, a first terminal device, and a second terminal device. The first terminal device is within the coverage range of the first base station, the second terminal device is within the coverage range of the second base station, and the first base station and the second base station can communicate with each other.

[0122] In the above two network architectures, the base station and the terminal device communicate through the Uu interface, and the terminal devices communicate through the PC5 interface. The wireless transmission between PC5 interfaces is also called SL transmission. The wireless communication link between the first terminal device and the second terminal device is called SL, and SL is used to transmit V2X services. The data packets sent on SL can be packets of a unicast connection or a multicast communication group. A unicast connection means that there is only one device at both the sending end and the receiving end, and in a multicast communication group, there is one device at the sending end and multiple devices at the receiving end.

[0123] The terminal device in this application is also called a terminal (Terminal), user equipment (UE), access terminal, user unit, user station, mobile station, mobile device, remote station, remote terminal, mobile device, user terminal, wireless communication device, user agent, or user device. The terminal device can be a station (ST) in a wireless local area network (WLAN), a cellular phone, a cordless phone, a session initiation protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA) device, a handheld device with wireless communication capabilities, a computing device, or other processing devices connected to a wireless modem, a vehicle-mounted device, a wearable device, and next-generation communication systems, such as terminal devices in a fifth-generation communication (5G) network or terminal devices in a future evolved public land mobile network (PLMN) network, and terminal devices in a new radio (NR) communication system, etc.

[0124] The base station can be an access point (AP) in a WLAN, a base transceiver station (BTS) in a Global System for Mobile Communication (GSM) or Code Division Multiple Access (CDMA), a node B (NB) in WCDMA, an evolved node B (eNB or eNodeB) in LTE, or a relay station or access point, or a new generation node B (gNodeB) in an NR system, etc. Optionally, the gNodeB can adopt a form with a separated central unit (CU) and distributed unit (DU). Exemplarily, the resource scheduling device referred to in this document can be a base station.

[0125] Figure 1 and Figure 2 This is only for illustration and not a limitation. The network architecture may also include more base stations and terminal devices.

[0126] Hereinafter, some terms in this application are explained to facilitate understanding by those skilled in the art.

[0127] (1) The unit in this application refers to a functional unit or a logical unit. It can be in software form and its function is realized by a processor executing program code; or it can be in hardware form.

[0128] (2) "Multiple" means two or more, and other quantifiers are similar. "And / or" describes the association relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the front and back associated objects. The ranges described by "above" or "below" include the boundary points.

[0129] (3) The explanations of the same nouns and concepts in different embodiments of this application can be referred to each other.

[0130] (4) The mode-3 resource allocation method involved in this application refers to the method by which the base station schedules resources for the terminal device, and the mode-4 resource allocation method refers to the method by which the terminal device selects resources by itself. Of course, the names of the above two resource allocation methods are not limited to mode 3 and mode 4, and can also be other names. Mode 3 and mode 4 are only used to distinguish the above two different resource allocation methods and do not constitute a limitation.

[0131] (5) The HARQ process involved in this application can be referred to as the SL HARQ process, which is used to process PC5 interface data packets (i.e., SL data packets), different from the Uu HARQ process for processing Uu interface data packets.

[0132] (6) The resource pool involved in this application refers to a collection of time-frequency resources.

[0133] In the prior art, after the data packet transmission on SL, the reliability of the data packet is ensured through a single blind retransmission. However, for high-reliability services, it is difficult to ensure the reliability of each data packet only relying on blind retransmission. Therefore, in the transmission method of this application, a hybrid automatic repeat request (HARQ) feedback retransmission mechanism is introduced in SL transmission. This retransmission mechanism is applicable to two resource allocation modes, mode-3 and mode-4. By introducing HARQ feedback, the reliability of data packets in SL transmission is improved.

[0134] Figure 3 It is a signaling flowchart of the transmission method provided in the first embodiment of this application. In this embodiment, the mode-3 resource allocation mode is adopted, as Figure 3 shown, and the method includes the following steps:

[0135] Step S101, the resource scheduling device sends downlink control information (DCI) to the first terminal device, and the DCI includes information of N SL transmission units.

[0136] Exemplarily, when there is data to be transmitted at the first terminal device, the first terminal device requests transmission resources from the resource scheduling device. The resource scheduling device allocates N SL transmission units to the first terminal device and sends the information of the N SL transmission units to the first terminal device through DCI. The N SL transmission units are used to transmit the data packets to be transmitted of the SL unicast connection or the multicast communication group. SL is the wireless communication link between the first terminal device and the second terminal device. The first terminal device is the sending device, and the second terminal device is the receiving device. The resource scheduling device can be a network device, a base station, or a terminal device for scheduling resources. When the resource scheduling device is a base station, the first terminal device and the second terminal device may be within the coverage of the same base station or within the coverage of different base stations.

[0137] N can be an integer greater than or equal to 1. Exemplarily, N can be a parameter predefined by the protocol or a parameter configured by the network. For unicast communication and multicast communication, the value of N can be the same or different. The SL transmission unit is the minimum transmission unit of the data packet transmitted on the SL. The transmission unit can also be referred to as a resource block. Each SL transmission unit can transmit one MAC PDU. The information of the N SL transmission units includes the identification information of the carriers where the N SL transmission units are located and the information of the time-frequency resources occupied by the N SL transmission units.

[0138] Exemplarily, the information of the time-frequency resources occupied by the N SL transmission units can include one or more of the following information: the number N of the SL transmission units, the frequency-domain position occupied by the SL transmission units, the time-domain interval between the SL transmission units, etc. When N is a parameter predefined by the protocol, N does not need to be carried in the DCI. The N SL transmission units are located on the same carrier. The identification information of the carrier where the N SL transmission units are located can be the identification of the carrier or the identification index of the carrier.

[0139] Optionally, the DCI can also include one or more of the following information: the information of the communication type, the information of the resources used by the second terminal device to send the HARQ feedback result to the first terminal device, the identification of the HARQ process (HARQ process id), the identification information of the bandwidth part (BWP), the identification information of the resource pool, the identification information of the unicast connection or the multicast communication group, etc. The communication type is a unicast communication type or a multicast communication type or a broadcast communication type. The identification of the unicast connection can be the identification of the second terminal device.

[0140] Exemplarily, the BWP corresponding to the BWP identification belongs to the SL carrier where the N SL transmission units are located. Multiple BWPs can be divided on the SL carrier where the N SL transmission units are located, and multiple resource pools can be divided on each BWP. If the BWP is defined on the SL carrier, the information of the N SL transmission units should not only include the identification information of the carrier where the N SL transmission units are located, but also include the identification information of the BWP where the N SL transmission units are located and the information of the resource pool.

[0141] Exemplarily, in addition to being carried in the DCI, the communication type can also be implicitly indicated by other means. For example, the resource scheduling device can configure different time-frequency resources for the unicast communication, multicast communication or broadcast communication of the first terminal device respectively, and configure the mapping relationship between the communication type and the carrier / resource pool / BWP. After receiving the DCI, the first terminal device can determine the communication type of this transmission according to the carrier / resource pool / BWP to which the N SL transmission units belong. The communication type of this transmission can also be regarded as the communication type of the N SL transmission units.

[0142] Step S102: The first terminal device uses an unused SL transmission unit among the N SL transmission units through the HARQ process used by the unicast connection or multicast communication group to transmit the data packet.

[0143] Exemplarily, after receiving the information of the N SL transmission units, the first terminal device delivers the information of the N SL transmission units to the MAC layer. The first terminal device may have established unicast connections with multiple terminals or belong to multiple multicast communication groups. Therefore, it is necessary to first determine the unicast connection or multicast communication group corresponding to this transmission. The first terminal device may determine the unicast connection or multicast communication group corresponding to this transmission according to the communication type from the unicast connections or multicast communication groups that have data packets to be transmitted and can be transmitted on the carrier / BWP / resource pool where the N SL transmission units are located. Exemplarily, the first terminal device may determine the unicast connection or multicast communication group corresponding to this transmission in the following several ways:

[0144] (1) Randomly select a unicast connection or multicast communication group from the unicast connections or multicast communication groups that have data packets to be transmitted and can be transmitted on the carrier / BWP / resource pool where the N SL transmission units are located as the unicast connection or multicast communication group corresponding to this transmission.

[0145] (2) Select the unicast connection or multicast communication group with the largest amount of data to be transmitted from the unicast connections or multicast communication groups that have data packets to be transmitted and can be transmitted on the carrier / BWP / resource pool where the N SL transmission units are located as the unicast connection or multicast communication group corresponding to this transmission.

[0146] (3) Select the unicast connection or multicast communication group with the highest quality of service (QoS) requirement from the unicast connections or multicast communication groups that have data packets to be transmitted and can be transmitted on the carrier / BWP / resource pool where the N SL transmission units are located as the unicast connection or multicast communication group corresponding to this transmission, where the highest QoS requirement may be the minimum delay, or the highest priority, or the highest data rate requirement, or the highest reliability requirement, etc.

[0147] (4) When the resource scheduling device carries the identification information of the unicast connection or multicast communication group in the DCI, the first terminal device determines the unicast connection or multicast communication group corresponding to this transmission according to the identification information of the unicast connection or multicast communication group indicated in the DCI.

[0148] Optionally, after determining the unicast connection or multicast communication group corresponding to this transmission, the first terminal device determines the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission from a set of HARQ processes corresponding to the SL carrier where the N SL transmission units corresponding to this transmission are located.

[0149] In this embodiment, the first terminal device may maintain a set of HARQ processes (or a HARQ entity) for multiple unicast connections or multicast communication groups respectively on one SL carrier. Each set of HARQ processes (or each HARQ entity) can only be used to process the data transmission of a specific unicast connection or multicast communication group. Correspondingly, a unicast connection or multicast communication group may correspond to multiple available SL carriers, and a set of HARQ processes (or a HARQ entity) is maintained for this unicast connection or multicast communication group on each available SL carrier. Among them, a HARQ entity includes a set of HARQ processes.

[0150] Alternatively, the first terminal device maintains a set of shared unicast HARQ processes (or a shared unicast HARQ entity) on one SL carrier, and / or the first terminal device maintains a set of shared multicast HARQ processes (or a shared multicast HARQ entity) on one SL carrier. Among them, the shared unicast HARQ processes and the shared multicast HARQ processes may be the same set of HARQ processes or different HARQ processes, and the shared multicast HARQ entity and the shared multicast HARQ entity may also be the same HARQ entity or different HARQ entities. The shared unicast HARQ entity / processes are used to process the data transmission of all unicast connections on this SL carrier, and the shared multicast HARQ entity / processes are used to process the data transmission of all multicast communication groups on this SL carrier. Correspondingly, a unicast connection or multicast communication group may correspond to multiple available SL carriers, and a set of shared unicast HARQ processes (or a shared unicast HARQ entity) or a set of shared multicast HARQ processes (or a shared multicast HARQ entity) is maintained on each available SL carrier.

[0151] For a multicast communication group, a multicast communication group includes multiple group members. One HARQ entity or a set of HARQ processes may be maintained for this multicast communication group on one SL carrier, or one HARQ entity or a set of HARQ processes may be maintained for each group member in this multicast communication group respectively on this SL carrier. This embodiment does not limit this.

[0152] Exemplarily, the unicast connection or multicast communication group corresponding to this transmission can only use the HARQ process maintained by the SL carrier where the N SL transmission units are located for data processing. When multiple groups of HARQ processes (or multiple HARQ entities) are set on the SL carrier where the N SL transmission units are located, if the DCI includes the identifier of the HARQ process, the first terminal device first determines the communication type, then determines the unicast connection or multicast communication group corresponding to this transmission according to the communication type, and then, according to the identifier of the HARQ process included in the DCI, determines, from a group of HARQ processes (or a group of HARQ processes included in the HARQ entity) corresponding to the unicast connection or multicast communication group corresponding to this transmission on the SL carrier where the N SL transmission units are located, that the HARQ process corresponding to the identifier of the HARQ process included in the DCI is the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission. If the DCI does not include the identifier of the HARQ process, the first terminal device first determines the communication type, then determines the unicast connection or multicast communication group corresponding to this transmission according to the communication type, and then selects an idle HARQ process from a group of HARQ processes (or a group of HARQ processes included in the HARQ entity) corresponding to the unicast connection or multicast communication group corresponding to this transmission on the SL carrier where the N SL transmission units are located as the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission, that is, associates the HARQ process with the unicast connection or multicast communication group identifier.

[0153] When only one group of shared unicast HARQ processes or one group of shared multicast HARQ processes is set on the SL carrier where the N SL transmission units are located, optionally, the terminal can maintain one group of shared unicast HARQ processes or one group of shared multicast HARQ processes for different communication types respectively on the SL carrier where the N SL transmission units are located, or can maintain one group of unicast HARQ processes or shared multicast HARQ processes shared by each communication type on the SL carrier where the N SL transmission units are located.

[0154] When the terminal can maintain a set of shared unicast HARQ processes or a set of shared multicast HARQ processes for multiple different communication types on the SL carrier where the N SL transmission units are located, the first terminal device first determines the communication type, and then, according to the communication type, determines a set of shared unicast HARQ processes or a set of shared multicast HARQ processes corresponding to the communication type. If the DCI includes the identifier of the HARQ process, the first terminal device determines, according to the identifier of the HARQ process included in the DCI, the HARQ process used for the unicast connection or multicast communication group corresponding to this transmission from the set of shared unicast HARQ processes or the set of shared multicast HARQ processes corresponding to the communication type. If the DCI does not include the identifier of the HARQ process, the first terminal device selects an idle HARQ process from the set of shared unicast HARQ processes or the set of shared multicast HARQ processes corresponding to the communication type as the HARQ process used for the unicast connection or multicast communication group corresponding to this transmission.

[0155] When the terminal maintains a set of shared unicast HARQ processes or shared multicast HARQ processes for each communication type on the SL carrier where the N SL transmission units are located, if the DCI includes the identifier of the HARQ process, the first terminal device can directly determine, from the set of shared unicast HARQ processes or the set of shared multicast HARQ processes for each communication type, that the HARQ process included in the DCI is the HARQ process used for this transmission. After determining the HARQ process, the first terminal device determines the unicast connection or multicast communication group corresponding to this transmission. If the DCI does not include the identifier of the HARQ process, the first terminal device selects an idle HARQ process from the set of shared unicast HARQ processes or the set of shared multicast HARQ processes for each communication type as the HARQ process used for this transmission. After determining the HARQ process, the first terminal device determines the unicast connection or multicast communication group corresponding to this transmission. Among them, the method for determining the unicast connection or multicast communication group used for this transmission refers to the four exemplary methods given above.

[0156] When the terminal maintains a set of shared unicast HARQ processes or shared multicast HARQ processes for each communication type on the SL carrier where the N SL transmission units are located, the first terminal device can also first determine the communication type, then determine the unicast connection or multicast communication group corresponding to this transmission according to the communication type, and then determine the HARQ process used for this transmission according to the identifier of the HARQ process indicated in the DCI, or select an idle HARQ process as the HARQ process used for this transmission.

[0157] In this embodiment, the first terminal device may carry the identifier of the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission in the sidelink control information (SCI) sent by the first terminal device to the second terminal device, so that the second terminal device can determine the HARQ process used for this transmission according to the HARQ process identifier carried in the SCI. Of course, the first terminal device may also not send the identifier of the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission to the second terminal device, and the second terminal device determines the HARQ process used for this transmission by other means. When the first terminal device performs an initial transmission or retransmission using a certain HARQ process, if the first terminal device receives an ACK feedback from the second terminal device, it is considered that the HARQ process is freed up.

[0158] Exemplarily, the N SL transmission units have an order. For an initial transmission, the first terminal device selects the first SL transmission unit, generates an SL MAC layer data packet by packetizing at the MAC layer, and uses the first SL transmission unit for transmission. For a retransmission, the first terminal device selects the Mth transmission unit to transmit the data in the buffer associated with the corresponding HARQ process, where 1 < M ≤ N. For a data packet, the first terminal device performs at least one transmission and at most N transmissions. If the initial transmission is successful, no retransmission is performed. If the initial transmission fails, retransmission is performed. If a certain retransmission is successful, no further retransmission is performed, and at most N - 1 retransmissions are performed. If the transmission still fails after N - 1 retransmissions, no further retransmission of this data packet is performed. It should be noted that the first terminal device processes the data packets for the initial transmission and retransmission using the same HARQ process.

[0159] Optionally, the SCI of the data packet carries indication information, which is used to indicate the second terminal device to perform HARQ feedback. The indication information may be the communication type, or the indication information is the identifier of the second terminal device or the identifier of the multicast communication group, or the indication information is the value of at least one-bit HARQ feedback field, and the value of the HARQ feedback field is used to indicate whether to perform HARQ feedback. For example, it is indicated by a 1-bit feedback_indicator field. When feedback_indicator = 1, it means that HARQ feedback is required. When feedback_indicator = 0, it means that HARQ feedback is not required.

[0160] Optionally, the second terminal device may determine whether HARQ feedback is required based on the resource location of the received SCI. For example, the base station configures the mapping relationship between the communication type and the carrier / resource pool / BWP for the second terminal device. The second terminal device determines whether the communication type is unicast communication or multicast communication based on the carrier / resource pool / BWP of the received SCI and the above-configured mapping relationship, and then HARQ feedback is required.

[0161] Optionally, it may also be indicated whether HARQ feedback is required by the scrambling method of the SCI. For example, for a unicast connection, it is scrambled using a unicast radio network temporary identity (RNTI), and for a multicast communication group, it is scrambled using a multicast RNTI. If the second terminal device successfully descrambles the SCI using the unicast RNTI or the multicast RNTI, it is determined that the data packet corresponding to the SCI requires HARQ feedback. Among them, the unicast RNTI may be the identifier of the unicast connection, and the multicast RNTI may be the identifier of the multicast communication group.

[0162] Of course, it may also be stipulated by the protocol that the second terminal device performs HARQ feedback on any received data packet. In this case, the first terminal device does not need to instruct the second terminal device to perform HARQ feedback.

[0163] Optionally, the SCI of the data packet may further include any one or more of the following information: information on the resources used for the HARQ feedback result, initial transmission or retransmission indication information, the redundancy version (RV) of the data packet, information on the carrier carrying the data packet, information on the BWP carrying the data packet, information on the resource pool carrying the data packet, the identifier of the HARQ process used by the unicast connection or the multicast communication group, the identifier of the unicast connection or the identifier of the multicast communication group, information on the communication type, and the identifier information of the first terminal device. Among them, the identifier of the unicast connection may be the identifier of the second terminal device.

[0164] Optionally, the information on the resources used for the HARQ feedback result may be implicitly determined by the time-frequency resource location where the SCI is located. For example, there is a fixed time interval between the time domain location of the resources used for the HARQ feedback result and the time domain location of the SCI, and there is a certain functional relationship between the frequency domain location of the resources used for the HARQ feedback result and the frequency domain location where the SCI is located. It may also be determined in combination with the time-frequency resource location where the SCI is located and the index value of the UE in the multicast communication group.

[0165] Step S103: The second terminal device decodes the data packet through the HARQ process used by the unicast connection or the multicast communication group corresponding to this transmission.

[0166] Exemplarily, the second terminal device receives a data packet and the SCI of the data packet, and first determines the unicast connection or multicast communication group corresponding to this transmission. The SCI includes one or more of the following information: communication type, identifier of the unicast connection or identifier of the multicast communication group, identifier of the first terminal device. The second terminal device may determine the unicast connection or multicast communication group corresponding to this transmission according to one or more of the communication type, identifier of the unicast connection or identifier of the multicast communication group, and identifier of the first terminal device included in the SCI. After determining the unicast connection or multicast communication group corresponding to this transmission, the second terminal device determines the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission.

[0167] In this embodiment, the second terminal device may maintain a set of HARQ processes (or a HARQ entity) for multiple unicast connections or multicast communication groups respectively on one SL carrier, or may maintain a set of shared unicast HARQ processes (or a shared unicast HARQ entity) on one SL carrier, and / or maintain a set of shared multicast HARQ processes (a shared multicast HARQ entity) on one SL carrier. Among them, the shared unicast HARQ process and the shared multicast HARQ process may be the same set of HARQ processes, or may be different HARQ processes, and the shared multicast HARQ entity and the shared multicast HARQ entity may also be the same HARQ entity, or may be different HARQ entities.

[0168] When both the first terminal device and the second terminal device maintain a set of HARQ processes (or a HARQ entity) for multiple unicast connections or multicast communication groups or each member of the multicast communication group respectively on one SL carrier; or, when the first terminal device maintains a set of shared unicast HARQ processes (or a shared unicast HARQ entity) or a set of shared multicast HARQ processes (or a shared multicast HARQ entity) on one SL carrier, and the second terminal device maintains a set of HARQ processes (or a HARQ entity) for multiple unicast connections or multicast communication groups respectively on one SL carrier, the SCI includes the identifier of the HARQ process used by the unicast connection or multicast communication group. The second terminal device determines, according to one or more of the following information included in the SCI: identifier of the HARQ process, identifier of the unicast connection or multicast communication group, identifier of the first terminal device, that the HARQ process corresponding to the identifier of the HARQ process included in the SCI is the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission from a set of HARQ processes (or a set of HARQ processes included in the HARQ entity) corresponding to the SL carrier carrying the data packet of the unicast connection or multicast communication group corresponding to this transmission.

[0169] When the first terminal device maintains a set of HARQ processes (or a HARQ entity) for each of multiple unicast connections, multicast communication groups, or members of a multicast communication group on a single SL carrier, and the second terminal device maintains a set of shared unicast HARQ processes (or a shared unicast HARQ entity) or a set of shared multicast HARQ processes (or a shared multicast HARQ entity) on a single SL carrier; or when both the first terminal device and the second terminal device maintain a set of shared unicast HARQ processes (or a shared unicast HARQ entity) or a set of shared multicast HARQ processes (or a shared multicast HARQ entity) on a single SL carrier, exemplarily, the HARQ process used by the corresponding unicast connection or multicast communication group for this transmission can be determined by the following two methods:

[0170] Method 1: The SCI does not carry the identification of the HARQ process, but carries the information of N SL transmission units. The second terminal device determines the SL carrier carrying the data packet according to the identification information of the carriers where the N SL transmission units are located, and selects an idle HARQ process on the SL carrier carrying the data packet as the HARQ process used by the corresponding unicast connection or multicast communication group for this transmission. The data received by the second terminal device on the first SL transmission unit is considered as newly transmitted data, and the data received on the subsequent SL transmission units is considered as retransmitted data. When the second terminal device finishes processing all N SL transmission units, the HARQ process is considered to be freed up. Optionally, when the second terminal device does not receive data on any one of the second to Nth SL transmission units, the HARQ process is considered to be freed up; optionally, when the second terminal device successfully decodes the transmitted data or after feeding back ACK to the first terminal device, the HARQ process is considered to be freed up.

[0171] Method 2: The SCI carries information such as the first terminal device identification information, HARQ process identification, unicast connection or multicast communication group identification, etc. After receiving the SCI of the initial transmission data packet from the first terminal device, the second terminal device selects an idle HARQ process and associates it with the first terminal device identification information, HARQ process identification, unicast connection or multicast communication group identification included in the SCI of the initial transmission data packet, and uses it as the HARQ process for processing this SL transmission. When the second terminal device receives the SCI of the retransmission data packet from the first terminal device, if there is a HARQ process associated with the first terminal device identification information, HARQ process identification information, unicast connection or multicast communication group identification in the SCI of the retransmission data packet, the retransmission data packet is delivered to the associated HARQ process for processing; if there is no HARQ process associated with the first terminal device identification information, HARQ process identification information, unicast connection or multicast communication group identification, an idle HARQ process can be selected and associated with the first terminal device identification information, HARQ process identification, unicast connection or multicast communication group identification in the SCI of the retransmission data packet to obtain the HARQ process used by the unicast connection or multicast communication group carrying the data packet. Optionally, the HARQ process can also be associated with the first terminal device identification information and HARQ process identification included in the SCI, without associating the HARQ process with the unicast connection or multicast communication group identification.

[0172] Optionally, the second terminal device can also ignore the SCI of the retransmission data packet. When the second terminal device successfully decodes the initial transmission data packet or the retransmission data packet or after feedback ACK to the first terminal device, the HARQ process for processing the initial transmission data packet or the retransmission data packet is considered to be freed up. Optionally, when an idle HARQ process is associated with the first terminal device identification information, HARQ process identification, unicast connection or multicast communication group identification in the SCI of the initial transmission data packet, a timer can be started for the HARQ process. When the HARQ process processes the retransmission data packet, the timer is restarted. When the timer times out, the HARQ process is considered to be freed up. The timing duration of the timer can be configured by the resource scheduling device to the second terminal device through system information or RRC message, or by the first terminal device to the second terminal device through RRC message, or can also be pre-configured in the storage device of the second terminal device.

[0173] After the second terminal device determines the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission, the data packet is delivered to the HARQ process for processing. If the data packet is an initial transmission data packet, the data packet is decoded. If the data packet is a retransmission data packet, the retransmission data can be directly decoded, or the retransmission data can be merged with the data stored in the cache associated with the HARQ process and then decoded.

[0174] Step S104, the second terminal device sends the HARQ feedback result of the data packet to the first terminal device.

[0175] The HARQ feedback result is an acknowledgement (ACK) or a negative acknowledgement (NACK). ACK indicates successful decoding, and NACK indicates decoding failure.

[0176] Step S105, in the case that the first terminal device does not receive the HARQ feedback result or the received HARQ feedback result indicates that the data packet transmission fails, the first terminal device uses the next unused SL transmission unit among the N SL transmission units to transmit the data packet.

[0177] Exemplarily, after the first terminal device sends the data packet, it listens for the HARQ feedback result on the resource used by the HARQ feedback result. If it does not receive an ACK or NACK, or receives an NACK, it retransmits the data packet using the next unused SL transmission unit. If the first terminal device receives an ACK on the resource used by the HARQ feedback result, it indicates that the data packet transmission is successful. Optionally, the first terminal device may trigger the sending of an uplink control information (UCI), and notify the resource scheduling device of the ACK result through the UCI. The UCI may also carry any one or more of the following information: information of the carrier carrying the data packet, information of the BWP carrying the data packet, information of the resource pool carrying the data packet, identification information of the unicast connection or multicast communication group, and identification of the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission.

[0178] When the first terminal device receives an ACK, optionally, the first terminal device may trigger an ACK feedback process. When there is uplink (UL) resource, the first terminal device generates and sends a MAC control element (CE), and notifies the resource scheduling device of the feedback ACK result through the MAC CE. The MAC CE may also carry any one or more of the following information: information of the carrier carrying the data packet, information of the BWP carrying the data packet, information of the resource pool carrying the data packet, identification information of the unicast connection or multicast communication group, and identification of the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission. Once the ACK feedback process is triggered, it is in a pending state until the MAC CE is sent out or all N SL transmission units allocated by the resource scheduling device have expired, and the ACK feedback process is cancelled.

[0179] Based on the ACK result sent by the first terminal device, the resource scheduling device learns that the data packet transmission is successful. If there are unused transmission units among the N transmission units, the resource scheduling device can allocate the unused transmission units to other terminal devices for use, avoiding waste of resources.

[0180] In this embodiment, the resource scheduling device indicates information of N SL transmission units to the first terminal device through DCI. The N SL transmission units are used for an SL to send a data packet of a unicast connection or a multicast communication group. The first terminal device uses an unused SL transmission unit among the N SL transmission units to transmit the data packet to the second terminal device through the HARQ process used by the unicast connection or the multicast communication group. The second terminal device sends a HARQ feedback result to the first terminal device according to the decoding result. When the first terminal device does not receive the HARQ feedback result or the received HARQ feedback result indicates that the data packet transmission fails, the first terminal device retransmits the data packet using the next unused SL transmission unit among the N SL transmission units. By introducing the HARQ feedback retransmission mechanism in the SL transmission, the reliability of the data packet transmitted in the SL is improved, and the resource scheduling device can avoid the large delay and waste of resource request caused by the terminal device requesting resources from the resource scheduling device every time it retransmits by allocating multiple SL transmission units at one time.

[0181] Embodiment 2

[0182] The differences between Embodiment 2 and Embodiment 1 include: In Embodiment 1, the first terminal device obtains information of N SL transmission units in the following manner: The first terminal device receives DCI sent by the resource scheduling device, and the DCI includes information of N SL transmission units. In Embodiment 2, the first terminal device obtains information of N SL transmission units in the following manner: The first terminal device determines information of N SL transmission units (i.e., mode 4 method) from the resource pool pre-configured by the resource scheduling device. When the first terminal device has data to be transmitted, it can first determine the communication type, or a specific unicast connection / multicast communication group, and determine information of N SL transmission units from the available resource pool according to the determined communication type or specific unicast connection / multicast communication group. Optionally, when the first terminal device has data to be transmitted, it can also first determine information of N SL transmission units from the available resource pool, and then determine which type of communication type the transmission unit is used to transmit data for, or specifically which unicast connection / multicast communication group the data is transmitted for. Other processes of Embodiment 2 are the same as those of Embodiment 1, and the description of Embodiment 1 is referred to here and will not be elaborated further.

[0183] Exemplarily, for a connected terminal device, the resource scheduling device may send the information of the resource pool through a radio resource control (RRC) message. For an idle terminal device, the resource scheduling device may broadcast the information of the resource pool through a system message, or the information of the resource pool may be pre-configured for the terminal device, for example, pre-configured in the storage device of the terminal. Subsequently, when the first terminal device has data to transmit, the required SL transmission unit is selected from the resource pool. Due to the different resource allocation methods, the indication methods of the HARQ process and the communication type are different from those in the first embodiment. In this embodiment, the resource scheduling device does not need to indicate the identifier of the HARQ process and the communication type used in this transmission through DCI, and only needs to indicate information such as the HARQ process identifier and / or communication type of this transmission in the SCI.

[0184] Figure 4 FIG. 4 is a signaling flowchart of the transmission method provided in the third embodiment of the present application. The resource allocation method in this embodiment is the same as that in the first embodiment, both are the mode3 method. However, in this embodiment, the resource scheduling device allocates only one SL transmission unit to the first terminal device each time. When retransmission is required, the first terminal device also needs to request the resource scheduling device to re-allocate the transmission resources.

[0185] As Figure 4 shown, the method provided in this embodiment includes the following steps:

[0186] Step S201, the resource scheduling device sends a first DCI to the first terminal device, and the first DCI includes the information of the first SL transmission unit.

[0187] Exemplarily, the first SL transmission unit is used to transmit the data packet to be transmitted of the SL unicast connection or the multicast communication group. The SL is the wireless communication link between the first terminal device and the second terminal device. The information of the first SL transmission unit includes the identification information of the carrier to which the first SL transmission unit belongs and the time-frequency resource information of the first SL transmission unit.

[0188] Exemplarily, the first DCI further includes any one or more of the following information: information on the communication type, the identifier of the HARQ process, the identifier of the BWP, the identifier information of the carrier, the identifier information of the resource pool, the identifier information of the unicast connection or the multicast communication group, the initial transmission or retransmission indication information, the redundancy version (RV) of the data packet, the resource information used by the second terminal device for HARQ feedback to the first terminal device on the SL link, etc. The communication type is a unicast communication type or a multicast communication type. The identifier information of the unicast connection may be the identifier of the second terminal device. The resource information used for HARQ feedback may include the resource information used by the second terminal device for HARQ feedback to the first terminal device and / or the resource information used by the first terminal device to forward the HARQ feedback result to the resource scheduling device.

[0189] When the communication type is not included in the first DCI, the communication type may also be implicitly indicated in other ways. The resource scheduling device may configure different time-frequency resources for the unicast communication / multicast communication / broadcast communication of the first terminal device. For example, the mapping relationship between the communication type and the carrier / resource pool / BWP is configured; the first terminal device may determine which communication type the first SL transmission unit is used for according to the carrier / resource pool / BWP to which the first SL transmission unit belongs.

[0190] Step S202: The first terminal device uses the HARQ process used by the unicast connection or the multicast communication group to transmit the data packet using the first SL transmission unit.

[0191] Exemplarily, the first terminal device first determines the unicast connection or the multicast communication group corresponding to this transmission. After determining the unicast connection or the multicast communication group corresponding to this transmission, it further determines the HARQ process for processing this transmission, that is, the HARQ process used by the unicast connection or the multicast communication group corresponding to this transmission; optionally, the first terminal device may also first determine the HARQ process for processing this transmission and then determine the unicast connection or the multicast communication group corresponding to this transmission. The determination method refers to the description of step S102 in Embodiment 1 and will not be elaborated here. The HARQ process used by the unicast connection or the multicast communication group corresponding to this transmission is associated with the identifier of the unicast connection or the multicast communication group, and the HARQ process identifier corresponding to this HARQ process may be carried in the SCI sent by the first terminal device to the second terminal device.

[0192] When the DCI indicates an initial transmission, the first terminal device performs MAC layer packet assembly to generate an SL MAC layer data packet and transmits the data packet using the first SL transmission unit; when the DCI indicates a retransmission, the first terminal device transmits the data in the buffer associated with the determined HARQ process.

[0193] Optionally, indication information is carried in the SCI of the data packet, and the indication information is used to indicate the second terminal device to perform HARQ feedback. The indication information may be a communication type, an identifier of a unicast connection, or an identifier of a multicast communication group, or a value of at least one-bit HARQ feedback field, and the value of the HARQ feedback field is used to indicate whether to perform HARQ feedback. The SCI may also be scrambled by a unicast RNTI and a multicast RNTI to indicate the second terminal device to perform HARQ feedback. Wherein, the identifier of the unicast connection may be the identifier of the second terminal device, the unicast RNTI may be the identifier of the unicast connection, and the multicast RNTI may be the identifier of the multicast communication group.

[0194] Optionally, the SCI of the data packet may further include any one or more of the following information: information on resources used for HARQ feedback results, initial transmission or retransmission indication information, RV of the data packet, information on the carrier carrying the data packet, information on the BWP carrying the data packet, information on the resource pool carrying the data packet, identifier of the HARQ process used by the unicast connection or multicast communication group, identifier of the unicast connection or identifier of the multicast communication group, information on the communication type, identifier of the first terminal device. Wherein, the information on resources used for HARQ feedback results may be implicitly determined by the time-frequency resource position where the SCI is located.

[0195] Step S203: The second terminal device decodes the data packet through the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission.

[0196] Exemplarily, after receiving the data packet, the second terminal device first determines the unicast connection or multicast communication group corresponding to this transmission, and further determines the HARQ process used by the unicast connection or multicast communication group. Wherein, the second terminal device may maintain a set of HARQ processes (or a HARQ entity) for multiple unicast connections or multicast communication groups respectively on one SL carrier, or maintain a set of shared unicast HARQ processes (or a shared unicast HARQ entity) or a set of shared multicast HARQ processes (or a shared multicast HARQ entity) on one SL carrier. Among them, the shared unicast HARQ processes and the shared multicast HARQ processes may be the same set of HARQ processes or different HARQ processes, and the shared multicast HARQ entities and the shared multicast HARQ entities may also be the same HARQ entity or different HARQ entities.

[0197] When the second terminal device maintains one HARQ entity / a set of HARQ processes for multiple unicast connections or multicast communication groups respectively on one SL carrier, or when the second terminal device maintains a set of shared unicast HARQ processes or multicast HARQ processes on one SL carrier, the method for determining the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission can refer to the description of Embodiment 1 and will not be elaborated here.

[0198] Exemplarily, after the second terminal device determines the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission, it delivers the data packet to this HARQ process for processing. If the data packet is a first transmission data packet, the data packet is decoded. If the data packet is a retransmission data packet, the retransmission data packet can be directly decoded, or the retransmission data packet can be merged with the data stored in the buffer associated with this HARQ process and then decoded.

[0199] Step S204: The second terminal device sends the HARQ feedback result of the data packet to the first terminal device.

[0200] Exemplarily, if the decoding is successful, the second terminal device sends an ACK to the first terminal device. If the decoding fails, the second terminal device sends a NACK to the first terminal device.

[0201] Step S205: The first terminal device sends the HARQ feedback result of the data packet to the resource scheduling device.

[0202] Exemplarily, after the first terminal device sends the data packet, it listens for the HARQ feedback result on the resource used for the HARQ feedback result. In this embodiment, whether the first terminal device receives an ACK or a NACK, or does not receive the HARQ feedback, it will send the HARQ feedback result to the resource scheduling device. Exemplarily, if the first terminal device receives the ACK sent by the second terminal device, it forwards the ACK to the resource scheduling device. If the first terminal device receives the NACK sent by the second terminal device or does not receive the HARQ feedback sent by the second terminal device, it will send a NACK to the resource scheduling device.

[0203] The first terminal device can trigger the sending of a UCI, and notify the resource scheduling device of the HARQ feedback result through this UCI. The UCI can also carry any one or more of the following information: information about the carrier carrying the data packet, information about the BWP carrying the data packet, information about the resource pool carrying the data packet, the identifier of the unicast connection or the identifier information of the multicast communication group, the identifier of the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission.

[0204] Alternatively, the first terminal device may trigger an ACK feedback process. When there is UL resource, the first terminal device generates and sends a MAC CE, and notifies the resource scheduling device of the HARQ feedback result through the MAC CE. The MAC CE may also carry any one or more of the following information: information of the carrier carrying the data packet, information of the BWP carrying the data packet, information of the resource pool carrying the data packet, identification of the unicast connection or identification information of the multicast communication group, and identification of the HARQ process used by the unicast connection or multicast communication group corresponding to this transmission.

[0205] Step S206, when the HARQ feedback result indicates that the data packet transmission fails, the resource scheduling device sends a second DCI to the first terminal device, and the second DCI includes information of the second SL transmission unit.

[0206] When the HARQ feedback result indicates that the data transmission fails, the resource scheduling device detects whether the retransmission times of the data packet reach the maximum number. If the retransmission times do not reach the maximum number, the resource scheduling device allocates a second SL transmission unit for the first terminal device. The information of the second SL transmission unit includes identification information of the carrier to which the second SL transmission unit belongs and time-frequency resource information of the second SL transmission unit, and the second SL transmission unit is used for retransmission. If the retransmission times reach the maximum number, or the HARQ feedback result indicates that the data transmission is successful, the resource scheduling device no longer allocates a second SL transmission unit.

[0207] It should be noted that step S206 is an optional step. When the HARQ feedback result indicates that the data packet transmission fails, the resource scheduling device may also perform other processing.

[0208] Step S207, the first terminal device transmits the data packet using the second SL transmission unit through the HARQ process used by the unicast connection or multicast communication group.

[0209] Exemplarily, the same HARQ process is used for the initial transmission and retransmission, and the first terminal device retransmits the data packet through the second SL transmission unit. After the first terminal device retransmits, it continues to monitor the HARQ feedback result.

[0210] In this embodiment, the resource scheduling device allocates an SL transmission unit to the first terminal device through the first DCI, uses the HARQ process of the unicast connection or the multicast communication group to transmit data packets using the first SL transmission unit, listens for the HARQ feedback result, and sends the HARQ feedback result to the resource scheduling device. When the HARQ feedback result indicates that the data transmission fails, the resource scheduling device allocates a second SL transmission unit to the first terminal device, and uses the HARQ process of the unicast connection or the multicast communication group to transmit data packets using the second SL transmission unit. Through the HARQ feedback retransmission mechanism, the high reliability of data packets can be ensured. The resource scheduling device decides whether to schedule retransmission resources according to the HARQ feedback result, avoiding the waste of resources that may be caused by scheduling multiple transmission units at one time.

[0211] Embodiment 4

[0212] The differences between Embodiment 4 and Embodiment 3 include: (1) In Embodiment 3, the first terminal device obtains the information of the transmission unit of the first SL in the following manner: the first terminal device receives the first DCI sent by the resource scheduling device, and the first DCI includes the information of the first SL transmission unit; in Embodiment 4, the first terminal device obtains the information of the transmission unit of the first SL in the following manner: the first terminal device determines the information of the first SL transmission unit from the resource pool preconfigured by the resource scheduling device. When the first terminal device has data to be transmitted, it can first determine the communication type, or a specific unicast connection / multicast communication group, and determine the information of the first SL transmission unit from the available resource pool according to the determined communication type or specific unicast connection / multicast communication group. Optionally, when the first terminal device has data to be transmitted, it can also first determine the information of the first SL transmission unit from the available resource pool, and then determine which type of communication data the transmission unit is used for, or specifically which unicast connection / multicast communication group the data transmission is for. (2) In Embodiment 3, the second terminal device sends the HARQ feedback result to the first terminal device, and the first terminal device then sends the HARQ feedback result to the resource scheduling device; in Embodiment 4, after decoding the data packet, the second terminal device sends the HARQ feedback result to the resource scheduling device according to the decoding result, without forwarding through the first terminal device. The other processes of Embodiment 4 are the same as those of Embodiment 3 and will not be elaborated here.

[0213] In addition, the first terminal device and the second terminal device may be within the coverage of the same base station or within the coverage of different base stations. Therefore, in Embodiment 4, the HARQ feedback result needs to be sent between the serving base stations of the first terminal device and the second terminal device through the interface between the base stations.

[0214] Embodiment 5

[0215] The differences between Embodiment 5 and Embodiment 3 include: (1) In Embodiment 3, the resource scheduling device indicates the information of the first SL transmission unit to the first terminal device through the first DCI. In Embodiment 5, the first terminal device determines the information of the first SL transmission unit from the resource pool pre-configured by the resource scheduling device; (2) After the data packet is transmitted, in Embodiment 3, the resource scheduling device decides whether to schedule retransmission resources according to the HARQ feedback result. If retransmission resources need to be scheduled, the resource scheduling device indicates the information of the second SL transmission unit for retransmission to the first terminal device through the second DCI. In Embodiment 4, when the first terminal device receives the HARQ feedback result sent by the second terminal device, it does not send the HARQ feedback result to the resource scheduling device. Instead, it decides whether to schedule retransmission resources according to the HARQ feedback result. If retransmission resources need to be scheduled, the first terminal device selects a second SL transmission unit from the pre-configured resource pool for retransmission. Other processes of Embodiment 5 are the same as those of Embodiment 3 and will not be elaborated here.

[0216] Figure 5 FIG. is a schematic structural diagram of a transmission device provided in Embodiment 6 of the present application. This device can be applied to the first terminal device, such as Figure 5 As shown, the device may include:

[0217] An obtaining module 11, configured to obtain information of N sidelink (SL) transmission units, where the N SL transmission units are used for transmitting data packets to be transmitted of the SL unicast connection or the multicast communication group, and the SL is a wireless communication link between the first terminal device and the second terminal device. Here, N is an integer greater than or equal to 1;

[0218] A sending module 12, configured to use a hybrid automatic repeat request (HARQ) process used by the unicast connection or the multicast communication group to transmit the data packet using an unused SL transmission unit among the N SL transmission units;

[0219] The sending module 12 is further configured to, when the first terminal device does not receive a HARQ feedback result or the received HARQ feedback result indicates that the data packet transmission fails, the first terminal device uses the next unused SL transmission unit among the N SL transmission units to transmit the data packet.

[0220] In one example, the obtaining module 11 is specifically configured to:

[0221] Receive downlink control information (DCI) sent by a resource scheduling device, where the DCI includes the information of the N SL transmission units, and the information of the N SL transmission units includes identification information of carriers where the N SL transmission units are located and time-frequency resource information occupied by the N SL transmission units.

[0222] In another example, the obtaining module 11 is specifically configured to:

[0223] Determine information of the N SL transmission units from a resource pool pre-configured by a resource scheduling device, where the information of the N SL transmission units includes identification information of carriers where the N SL transmission units are located and information of time-frequency resources occupied by the N SL transmission units.

[0224] In one example, the DCI further includes any one or more of the following information: communication type, identification of a HARQ process, and identification of a partial bandwidth;

[0225] The communication type is a unicast communication type or a multicast communication type.

[0226] Optionally, the device further includes:

[0227] A first determination module 13, configured to determine the unicast connection or the multicast communication group from unicast connections or multicast communication groups that have data packets to be transmitted and are transmitted on carriers where the N SL transmission units are located according to the communication type;

[0228] A second determination module 14, configured to determine a HARQ process used by the unicast connection or the multicast communication group from a group of HARQ processes corresponding to an SL carrier where the N SL transmission units are located according to the identification of the HARQ process included in the DCI.

[0229] The device provided in this application can be used to execute the methods performed by the first terminal in Embodiment 1 and Embodiment 2. The specific implementation methods and technical effects are similar and will not be elaborated here.

[0230] Figure 6 It is a schematic structural diagram of a transmission device provided in Embodiment 7 of this application. This device can be applied to a first terminal device, such as Figure 6 As shown, the device may include:

[0231] An obtaining module 21, configured to obtain information of a first sidelink (SL) transmission unit, where the first SL transmission unit is used to transmit data packets to be transmitted of a unicast connection or a multicast communication group, and the SL is a wireless communication link between the first terminal device and a second terminal device;

[0232] A sending module 22, configured to transmit the data packet using the first SL transmission unit through a hybrid automatic repeat request (HARQ) process corresponding to the unicast connection or the multicast communication group;

[0233] The obtaining module 21 is further configured to obtain information of a second SL transmission unit when the data packet transmission fails;

[0234] The sending module 22 is further configured to retransmit the data packet by using the second SL transmission unit.

[0235] In one example, the obtaining module 21 is specifically configured to:

[0236] Receive first downlink control information DCI sent by a resource scheduling device, where the first DCI includes information of the first SL transmission unit, and the information of the first SL transmission unit includes identification information of a carrier where the first SL transmission unit is located and information of time-frequency resources occupied by the first SL transmission unit;

[0237] Receive second DCI sent by the resource scheduling device, where the second DCI includes information of the second SL transmission unit, and the information of the second SL transmission unit includes identification information of a carrier where the second SL transmission unit is located and time-frequency resource information of the second SL transmission unit, and the second SL transmission unit is allocated by the resource scheduling device according to HARQ feedback results reported by the first terminal device or the second terminal device.

[0238] In another example, the obtaining module 21 is specifically configured to:

[0239] Determine the information of the first SL transmission unit or the information of the second SL transmission unit from a resource pool pre-configured by a resource scheduling device, where the information of the first SL transmission unit includes identification information of a carrier where the first SL transmission unit is located and information of time-frequency resources occupied by the first SL transmission unit, and the information of the second SL transmission unit includes identification information of a carrier where the second SL transmission unit is located and information of time-frequency resources occupied by the second SL transmission unit.

[0240] In one example, the first DCI further includes at least one of the following information: information of a communication type, an identifier of a HARQ process, and an identifier of a partial bandwidth;

[0241] The communication type is a unicast communication type or a multicast communication type.

[0242] Optionally, the apparatus further includes:

[0243] A first determination module 23, configured to determine the unicast connection or the multicast communication group from a unicast connection or a multicast communication group that has a data packet to be transmitted and is transmitted on a carrier where the first SL transmission unit is located according to the communication type;

[0244] A second determination module 24, configured to determine, according to an identifier of a HARQ process included in the first DCI, a HARQ process used by the unicast connection or the multicast communication group from a group of HARQ processes corresponding to an SL carrier where the first SL transmission unit is located in the unicast connection or the multicast communication group.

[0245] The apparatus provided in this application can be used to execute the method performed by the first terminal in Embodiments 2 to 5. The specific implementation methods and technical effects are similar and will not be elaborated here.

[0246] Figure 7 FIG. is a schematic structural diagram of a transmission apparatus provided in Embodiment 8 of this application. This apparatus can be applied to a resource scheduling device, such as Figure 7 As shown, the apparatus may include:

[0247] A sending module 31, configured to send information of N sidelink (SL) transmission units to a first terminal device, where the N SL transmission units are used for transmitting data packets to be transmitted of a unicast connection or a multicast communication group of the SL, and the SL is a wireless communication link between the first terminal device and a second terminal device, where N is an integer greater than or equal to 1;

[0248] A receiving module 32, configured to receive a HARQ feedback result sent by the first terminal device or the second terminal device.

[0249] In one example, the sending module 31 is specifically configured to:

[0250] Send downlink control information (DCI) to the first terminal device, where the DCI includes information of the N SL transmission units, and the information of the N SL transmission units includes identification information of carriers where the N SL transmission units are located and information of time-frequency resources occupied by the N SL transmission units.

[0251] The apparatus provided in this application can be used to execute the method performed by the resource scheduling device in Embodiments 1 to 5. The specific implementation methods and technical effects are similar and will not be elaborated here.

[0252] Optionally, in Embodiments 6 to 8, multiple groups of HARQ processes are set on the SL carrier where the SL transmission unit is located, and each group of HARQ processes in the multiple groups of HARQ processes can only be used for data transmission of one unicast connection or one multicast communication group; or,

[0253] A set of shared unicast HARQ processes or multicast HARQ processes is provided on the SL carrier where the SL transmission unit is located. The shared unicast HARQ process can be used for data transmission of all unicast connections on the SL carrier where the SL transmission unit is located, and the shared multicast HARQ process can be used for data transmission of all multicast communication groups on the SL carrier where the SL transmission unit is located.

[0254] Optionally, in Embodiments 6 to 8, indication information is carried in the SCI of the data packet, and the indication information is used to indicate the second terminal device to perform HARQ feedback;

[0255] Wherein, the indication information is a communication type, and the communication type is a unicast communication type or a multicast communication type; or,

[0256] The indication information is an identifier of the second terminal device or an identifier of the multicast communication group; or,

[0257] The indication information is a value of at least one-bit HARQ feedback field, and the value of the HARQ feedback field is used to indicate whether to perform HARQ feedback.

[0258] Optionally, in Embodiments 6 to 8, the SCI of the data packet further includes any one or more of the following information: information on resources used for the HARQ feedback result, initial transmission or retransmission indication information, redundancy version of the data packet, information on the carrier carrying the data packet, information on the partial bandwidth BWP carrying the data packet, identifier of the HARQ process used by the unicast connection or the multicast communication group, information on the N SL transmission units, identifier of the unicast connection or the multicast communication group, information on the communication type, identifier of the first terminal device.

[0259] Figure 8 It is a schematic structural diagram of a transmission device provided in Embodiment 9 of the present application. This device can be applied to a second terminal device, such as Figure 8 As shown, this device may include:

[0260] A receiving module 41, configured to receive a data packet and sidelink control information SCI, where the SCI includes one or more of the following information: communication type, identifier of a unicast connection or identifier of a multicast communication group;

[0261] A first determination module 42, configured to determine a unicast connection or a multicast communication group corresponding to this transmission according to the communication type, and / or, the identifier of the unicast or the identifier of the multicast communication group, where the communication type is a unicast communication type or a multicast communication type;

[0262] A decoding module 43, configured to decode the data packet by using a hybrid automatic repeat request (HARQ) process used by a unicast connection or a multicast communication group corresponding to the current transmission.

[0263] A sending module 44, configured to send a HARQ feedback result to a first terminal device or a resource scheduling device according to the decoding result, where data is transmitted between the first terminal device and a second terminal device through a sidelink.

[0264] In one example, the SCI further includes an identifier of the HARQ process, an identifier of the first terminal device, and identifier information of an SL carrier carrying the data packet. Optionally, the apparatus further includes:

[0265] A second determination module 45, configured to determine a HARQ process used by the unicast connection or the multicast communication group corresponding to the current transmission from a group of HARQ processes corresponding to the SL carrier carrying the data packet and corresponding to the unicast connection or the multicast communication group corresponding to the current transmission according to the identifier of the HARQ process, the identifier of the first terminal device, the identifier of the unicast connection, or the identifier of the multicast communication group included in the SCI.

[0266] Optionally, multiple groups of HARQ processes are set on the SL carrier carrying the data packet, and each group of HARQ processes in the multiple groups of HARQ processes can only be used for data transmission of one unicast connection or one multicast communication group; or,

[0267] A group of shared unicast HARQ processes or multicast HARQ processes are set on the SL carrier carrying the data packet, the shared unicast HARQ processes can be used for data transmission of all unicast connections on the SL carrier carrying the data packet, and the shared multicast HARQ processes can be used for data transmission of all multicast communication groups on the SL carrier carrying the data packet.

[0268] The apparatus provided in this application can be used to execute the methods executed by the second terminal device in Embodiments 1 to 5. The specific implementation methods and technical effects are similar and will not be elaborated here.

[0269] Figure 9 It is a schematic structural diagram of a terminal device provided in Embodiment 10 of this application. As Figure 9 shown, the terminal device provided in this embodiment includes a processor 51, a memory 52, and a transceiver 53. The memory 52 is used to store instructions, the transceiver 53 is used to communicate with other devices, and the processor 51 is used to execute the instructions stored in the memory 52 so that the terminal device executes the method steps executed by the first terminal device and the second terminal in Embodiments 1 to 5 of this application. The specific implementation manners and technical effects are similar and will not be elaborated here.

[0270] Figure 10 The following is a schematic structural diagram of the resource scheduling device provided in the eleventh embodiment of the present application. As Figure 10 shown, the resource scheduling device provided in this embodiment includes: a processor 61, a memory 62, and a transceiver 63. The memory 62 is used to store instructions, the transceiver 63 is used to communicate with other devices, and the processor 61 is used to execute the instructions stored in the memory 62, so that the resource scheduling device executes the method steps executed by the resource scheduling device in Embodiments 1 to 5 of the present application. The specific implementation manners and technical effects are similar and will not be elaborated here.

[0271] The twelfth embodiment of the present application provides a computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are executed, the computer executes the method steps executed by the first terminal device and the second terminal device in Embodiments 1 to 5 of the present application. The specific implementation manners and technical effects are similar and will not be elaborated here.

[0272] The thirteenth embodiment of the present application provides a computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are executed, the computer executes the method steps executed by the resource scheduling device in Embodiments 1 to 5 of the present application. The specific implementation manners and technical effects are similar and will not be elaborated here.

[0273] The fourteenth embodiment of the present application provides a system-on-chip or system chip. The system-on-chip or system chip can be applied to a terminal device. The system-on-chip or system chip includes: at least one communication interface, at least one processor, and at least one memory. The communication interface, the memory, and the processor are interconnected through a bus. The processor executes the instructions stored in the memory, so that the terminal device can execute the method steps executed by the first terminal device and the second terminal device in Embodiments 1 to 5 of the present application. The specific implementation manners and technical effects are similar and will not be elaborated here.

[0274] The fifteenth embodiment of the present application provides a system-on-chip or system chip. The system-on-chip or system chip can be applied to a resource scheduling device. The system-on-chip or system chip includes: at least one communication interface, at least one processor, and at least one memory. The communication interface, the memory, and the processor are interconnected through a bus. The processor executes the instructions stored in the memory, so that the resource scheduling device can execute the method steps executed by the resource scheduling device in Embodiments 1 to 5 of the present application. The specific implementation manners and technical effects are similar and will not be elaborated here. Exemplarily, the resource scheduling device can be a base station, an access node in a radio access network, or other network devices on the network side that provide services for terminal devices.

[0275] It can be understood that the processor used in the resource scheduling device or the terminal device in the embodiments of the present application may be a central processing unit (CPU), a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It can implement or execute various exemplary logic blocks, modules, and circuits described in connection with the disclosure of the present application. The processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and so on.

[0276] The bus described in the embodiments of the present application may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, or the like. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the buses in the drawings of the present application are not limited to only one bus or one type of bus.

[0277] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0278] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0279] In addition, the functional units in the various embodiments of the present application can be integrated in one processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of a combination of hardware and software functional units.

[0280] The integrated units implemented in the form of software functional units can be stored in a computer-readable storage medium. The above-mentioned software functional units are stored in a storage medium and include several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) or a processor to execute some steps of the methods described in various embodiments of the present application. The foregoing storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM), random access memories (RAM), magnetic disks, or optical discs.

Claims

1. A transmission method, applied to sidelink (SL) communication, characterized in that including: receiving a data packet and sidelink control information (SCI) sent by a first terminal device, where the SCI includes an identifier of a hybrid automatic repeat request (HARQ) process, an identifier of the first terminal device, and an identifier of a second terminal device, and the data packet is an initial transmission data packet; selecting an idle HARQ process to associate with the identifier of the first terminal device, the identifier of the HARQ process, and the identifier of the second terminal device, and using the selected idle HARQ process as the HARQ process for processing the current transmission.

2. The method according to claim 1, wherein The method includes: determining a first resource according to the time domain resource position where the SCI is located, where the first resource is used to send a HARQ feedback result to the first terminal device; sending the HARQ feedback result to the first terminal device on the first resource.

3. The method according to claim 2, wherein The HARQ feedback result includes an acknowledgement (ACK) or a negative acknowledgement (NACK).

4. The method according to any one of claims 1 to 3, characterized in that The SL is a wireless communication link between the first terminal device and the second terminal device.

5. A transmission method, applied to sidelink (SL) communication, characterized in that, including: sending a data packet and sidelink control information (SCI) to a second terminal device, where the SCI includes an identifier of a hybrid automatic repeat request (HARQ) process, an identifier of a first terminal device, and an identifier of the second terminal device, and the data packet is an initial transmission data packet; wherein, the identifier of the hybrid automatic repeat request (HARQ) process, the identifier of the first terminal device, and the identifier of the second terminal device included in the SCI are used to associate an idle HARQ process, and the idle HARQ process is used to process the current transmission.

6. The method according to claim 5, characterized in that, The method further includes: receiving a HARQ feedback result sent by the second terminal device on a first resource, where the first resource is determined according to the time-frequency resource position where the SCI is located.

7. The method according to claim 6, wherein The HARQ feedback result includes an acknowledgement (ACK) or a negative acknowledgement (NACK).

8. The method according to claim 7, wherein The method further includes: in the case where the HARQ feedback result is an acknowledgement (ACK), forwarding the ACK to a resource scheduling device; or, in the case where the HARQ feedback result is a negative acknowledgement (NACK) or in the case where no HARQ feedback sent by the second terminal device is received, the first terminal device sending a NACK to the resource scheduling device.

9. The method according to any one of claims 6 - 8, characterized in that, notifying the resource scheduling device of the HARQ feedback result through uplink control information (UCI).

10. The method according to any one of claims 6-8, characterized in that, The SL is a wireless communication link between the first terminal device and the second terminal device.

11. A communication device, characterized in that, including a module for executing the method according to any one of claims 1 to 4 or the method according to any one of claims 5 to 10.

12. A device, characterized in that, The device includes: at least one processor and a communication interface, where the communication interface is used for the device to interact with other communication devices, and when computer instructions are executed in the at least one processor, the device implements the method according to any one of claims 1 to 4.

13. A device, characterized in that, The apparatus includes: at least one processor and a communication interface, the communication interface being used for the apparatus to interact with other communication devices, and when computer instructions are executed in the at least one processor, the apparatus implements the method according to any one of claims 5 to 10.

14. A computer-readable medium, characterized in that, It includes computer instructions, and when the computer instructions run on a computer, the computer is caused to execute the transmission method according to any one of claims 1 to 10.

15. A computer program product, characterized in that, The computer program product includes computer instructions, and when the computer instructions run on a computer, the computer is caused to execute the transmission method according to any one of claims 1 - 10.

16. A communication system, characterized in that, It includes: The apparatus according to claim 12 and the apparatus according to claim 13.

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